The following description is provided to assist the understanding of the reader. None of the information provided or references cited is admitted to be prior art.
Carbon nanotubes (CNTs) have increasingly been used as chemical sensors and probes. Such uses often require dispersions of CNTs in a liquid or solid host medium. However, creating such dispersions of CNTs in the host medium has been a major challenge. For example, CNTs tend to agglomerate and bundle together causing many site defects in a CNT composite. Functionalization of the CNT is one method to prevent agglomeration and improves the compatibility of CNT and the host material.
The functionalization process is not without drawbacks: it is often slow, difficult, and uses harmful chemicals. For example, CNT may be functionalized with an amino group. This functionalization, however, may lead to alteration of the desired properties of the CNT (e.g., its hydrophobic character, chirality, effective length, cross sectional area of the CNT, etc.). Additionally, for single wall carbon nanotubes (SWNTs), functionalization may lead to the formation of undesirable cross-linked structures, which may ultimately change the native signature characteristic of this unique nanostructure.
Unless functionalized, CNTs, such as SWNTs, are hydrophobic. As a result, CNTs often have difficulty interacting with certain molecules, such as amphiphilic molecules (e.g., amphiphilic lipids, detergents, etc). In particular, when these amphiphilic molecules are in an aqueous state, they tend to take on complex vesicular or micelle forms, that encapsulate the hydrophobic CNT, and prevent formation of an interface in which the CNTs directly interact with the entire structures of amphiphilic molecules. Thus, many challenges remain with respect to using CNTs as chemical sensors and probes.